The disclosure relates to a hand device having a retrograde hand, an electronic timepiece, a hand driving method of the electronic timepiece and a recording medium.
The retrograde is a French astronomical terminology indicative of the antecedence. In a timepiece, the retrograde means a mechanism configured to display time, a calendar and the like by a hand configured to repetitively move. Herein, an example of a day display in which seven days are set as one period is described. A day hand of the retrograde moves from Monday, which is a starting point, to Sunday, which is an ending point, via Tuesday, Wednesday, Thursday, Friday and Saturday by one day. Also, when switching from Sunday to next Monday, the day hand switches to the starting point in a moment. Thereby, the entertainment characteristic is secured by the movement of the hand, which is pleasure to user's eyes.
For example, an Abstract of a Japanese Patent Application Publication No. 2005-315669A discloses “A day display area is made into a fan-shaped display of a retrograde tone, a year display area and an alarm setting state check area are arranged in a surplus area thereof, and the corresponding information is displayed by a day hand 7. A display content of the day hand 7 can be arbitrarily changed by an external operation in a current time display mode. Thereby, it is possible to display the information as much as possible in a limited display area, to check the information on the current time display mode without changing a mode to call a predetermined mode, and to simplify the operation specifications.”
According to the invention disclosed in Patent Document 1, it is possible to display a plurality of operation functions by the retrograde. However, according to this configuration, the current operation mode is simply displayed and the user cannot easily understand an operation state of a device such as a function shift operation and the like by the movement of the hand.
Also, the retrograde disclosed in Patent Document 1 is implemented by providing an area in which it can rotate over one week and using a fan-shaped area of a part thereof. Thereby, even though the hand is not rotatively driven in both clockwise and counterclockwise directions, the hand is rotatively driven only in one direction, so that the retrograde can be implemented. However, as compared to the retrograde configured to reciprocally move the hand in the fan-shaped area, the display area is smaller, so that the visibility is lower.
Also, there is a retrograde configured to gradually accumulate the repulsive energy in an elastic body such as a spring, a windup spring or the like as the hand moves, and to switch the hand to the starting point by using the repulsive energy at the ending point. According to this mechanism, it is possible to move the hand to the fan-shaped area. However, since the energy is accumulated in the elastic body, the movement of the hand is limited to only one direction.